In the past, valves have been designed for opening and closing mechanisms that combine the action of springs with electromagnets. However, the earlier designs did not operate quickly enough to open and close the valves with sufficient speed. For example, valves using spring action could not be designed with the speed normally required for the opening and closing of an internal combustion engine's intake and exhaust valves, or for the speed required for air compressors.
One of the reasons why the earlier valve designs could not operate at the desired high speeds is the mass of the moving core assembly. In previous designs, the mass of the moving core piece providing the return path for the magnetic flux was not sufficiently small so that it could be accelerated as quickly as desired for certain applications, such as modern internal combustion engines. Therefore, a need existed for a lightweight core design for use in an electromagnetically actuated valve.
Another problem with the valves of the prior art is caused by hysteresis, or a lagging in the value of magnetization in a magnetic material due to a change in magnetizing forces. More specifically, in the previously designed electromagnetic actuators, eddy currents and a residual flux remain in the magnetic material when the electromagnet in the valve is deenergized, causing a delay in the release of the core and therefore a decrease in the speed of the valve. Therefore, it is desirable to eliminate the residual flux, and thereby instantaneously decay the magnetic forces to zero such that the actuator reacts quicker.